Abstract The west coast of India is one of the important geothermal provinces that hosts many thermal springs of varying discharge characteristics. A total of twenty thermal springs have been reported in this region falling into two different suites of geological formations. Two low temperature geothermal springs located in the south Konkan region were studied with the objectives (1) to understand the geochemical evolution, (2) to identify the recharge source and (3) to propose a reservoir temperature. The hydrogeological and geochemical investigations were carried out on two geothermal springs, viz. Bandaru and Irde, both located in the Dakshina Kannada district of the Karnataka state, India. In this region, low-temperature geothermal activity has been reported in the form of the evolution of warm water from thermal spring systems with a notable presence of faults/lineaments in the geological formation. These faults enable the upward flow of geothermally heated water. The hydrochemistry of water samples was analyzed to determine the dominant hydrogeochemical processes in the region. These thermal springs are categorised as Na-HCO3 type facies. The thermal water is of a moderately alkaline nature like other geothermal springs of the west coast of India. Based on the results for major and trace element concentrations it was found that the hydrochemical process was mainly controlled by the dissolution of silicate minerals with a marginal influence from anthropogenic activity. Evaluation of δD and δ18O stable isotope data suggested that the thermal springs and adjacent surface and groundwater were of meteoric origin. Reservoir temperature was estimated with Na-K-Ca, K2/Mg, quartz and chalcedony geothermometers. The results suggest that the reservoir under consideration is a low enthalpy reservoir with temperatures ranging between 55 and 86 °C.

中文翻译：

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印度南康坎地区低温温泉水化学、地温测量及成因

摘要 印度西海岸是重要的地热省份之一，拥有许多不同排放特征的温泉。据报道，该地区共有 20 个温泉落入两种不同的地质构造。研究了位于南康坎地区的两个低温地热泉，目的是 (1) 了解地球化学演化，(2) 确定补给源和 (3) 提出储层温度。对两个地热泉进行了水文地质和地球化学调查，即。Bandaru 和 Irde，都位于印度卡纳塔克邦的 Dakshina Kannada 区。在这个地区，据报道，低温地热活动的形式是温泉系统中的温水演化，地质构造中存在显着的断层/线条。这些断层使地热水向上流动。分析水样的水化学以确定该地区的主要水文地球化学过程。这些温泉被归类为 Na-HCO3 型相。与印度西海岸的其他地热泉一样，温泉水具有中等碱性。根据主要和微量元素浓度的结果发现，水化学过程主要受硅酸盐矿物的溶解控制，人为活动的影响很小。对 δD 和 δ18O 稳定同位素数据的评估表明，温泉以及邻近的地表和地下水为大气源。储层温度是用 Na-K-Ca、K2/Mg、石英和玉髓地温计估算的。结果表明，所考虑的储层是一个低焓储层，温度范围在 55 到 86 °C 之间。